The leaders also held an exchange of views with Ukraine's Prime Minister Arseniy Yatsenyuk.
Russia's actions condemned
In the joint statement, the EU leaders condemned Russia's unprovoked violation of Ukrainian sovereignty and territorial integrity. They called on Russia to immediately withdraw its armed forces and allow immediate access for international monitors.
The EU leaders consider the decision of Crimea's Supreme Council to hold a referendum on Crimea joining the Russian Federation to be contrary to the Ukrainian constitution and therefore illegal.
Peaceful solution through negotiations
The solution to the crisis should be found through negotiations between the Governments of Ukraine and the Russian Federation, including through potential multilateral mechanisms, the leaders stated.
EU ready for dialogue with both Russia and Ukraine
The EU has important relations with both Russia and Ukraine and stands ready to engage with both countries bilaterally and also in broader multilateral initiatives.
"We want a solution in full respect of international law and the territorial integrity of countries," said President Van Rompuy. "The situation must de-escalate – and failure by Russia to do so will have serious consequences on our bilateral relationship."
Actions taken
The leaders confirmed the actions agreed by the EU foreign ministers on 3 March, to suspend bilateral talks with the Russian Federation on visa matters and on the New Agreement.
They support the decision of the European G8 members and the EU institutions to suspend their participation in G8 Summit preparations scheduled to take place in Sochi in June 2014.
Additional measures to be considered
The negotiations between Ukraine and Russia should start within the next few days. In the absence of results within a limited timeframe the European Union will decide on additional measures, such as travel bans, asset freezes and the cancellation of the EU-Russia summit.
Any further steps by the Russian Federation to destabilise the situation in Ukraine "would lead to severe and far-reaching consequences for relations between the European Union and the Russian Federation, which will include a broad range of economic areas", reads the statement.
Association agreement with Ukraine
The leaders reiterated the EU's commitment to signing the Association Agreement with Ukraine, including a Deep and Comprehensive Free Trade Area. It was decided to sign the political chapters of the Agreement before the Ukrainian elections of 25 May.
Financial support to Ukraine and other measures
The leaders welcomed the comprehensive assistance package that the European Commission presented on 5 March. They asked for all the necessary steps to be taken rapidly to ensure the package's early implementation.
"We remain committed to the visa liberalisation process, to encouraging contacts between the citizens of the EU and of Ukraine. We stand ready to assist also on energy security," said President Van Rompuy.
